Frankly, I prefer buying from exchanges as well. They're relatively safer, certainly less of a hassle and incredible fast.
Especially with my local exchange where I buy directly from the exchange, no need to look for p2p. The prices are steady and support is very responsive.
Of course, there are cons, as there always is. I had to verify. (No choice really as the service was really convenient and choice was limited if not nonexistent, especially if I also to wanted convert to fiat.)
Anyway, possible reasons I can see that would make me buy from an individual:
1. Trust - If I personally knew the person or is recommended by someone I really trust.(not about reputation or forum trust)
2. Price - there's just no possibility of a discount with high volume buys from exchanges.
3. Convenience - if we both could agree on favorable/easy enough terms. (where to send,what to use)
4. Step 1 is a must.